This invention relates to needle-suture combinations and more particularly to needle-suture combinations wherein the needle is attached to the suture in a nonpermanent manner which allows the needle to be deliberately pulled off the suture after completion of the suturing procedure.
In many surgical procedures, surgeons use an interrupted suturing technique which employs a suture thread and an eyed needle. The needle is threaded by the nurse and the surgeon takes one pass through the tissue using a needle holder. He slips the needle off the suture, returns the needle to the nurse, and is ready for another threaded needle from the nurse. An assistant follows behind and ties each suture.
Some surgeons find this technique preferable to using a needled suture which requires cutting the needle from the suture with a scissors after each pass. However, the time required for threading individual needles delays the suturing procedure which is undesirable for the welfare of the patient and efficient utilization of expensive operating room time.
It has recently been suggested to use needle-suture combinations in which the needle and the suture are readily separable from each other after completion of the suturing procedure to provide the surgeon with the convenience of needled sutures without the inconvenience of requiring the needle to be cut off each suture. Several methods have been devised for preparing needle-suture combinations in which the pulloff values, or the force required to separate the needle from the suture by a straight, steady pull is within the desired range. One approach to this problem is described in U.S. Pat. No. 3,890,975 where the needle is attached to the suture by controlled swaging so that the force required to pull the needle off the suture is from about 3 to 26 ounces (0.085-0.736 kg). The needles are attached with sufficient security to perform regular suturing procedures, and yet are readily removed by the deliberate action of the surgeon upon completion of the procedure.
Another approach to controlled release needle-suture combinations is described in U.S. Pat. No. 3,779,169 where a suture is bonded in an open channel of a surgical needle with an adhesive composition which allows the suture to be peeled from the channel by a force of about 3 to 26 ounces when the suture is at an angle of 90.degree. to the needle channel. Other issued U.S. patents describing needle-suture combinations having controlled release properties include U.S. Pat. Nos. 3,875,946; 3,924,630; 3,926,194; 3,949,756; and 3,943,933.
Many of the prior art controlled release needle-suture combinations depend upon swaging to attach the needle to the suture. Controlled needle release values in the desired range are obtained either by controlling the degree of swaging, by partially withdrawing the suture from the swaged needle until the holding forces are reduced to the desired pulloff values, or by providing the securely swaged suture with a breakable segment adjacent the needle. Variations in suture composition or size, or in the size and finish of the needle barrel opening can affect needle attachment and make it difficult for the suture manufacturer to maintain pulloff values within the desired range.
U.S. Pat. No. 3,779,169 supra depends upon adhesive forces rather than compression by mechanical swaging to obtain the desired release values, but is only effective with open channel needles which allow the suture to be peeled out of the channel.
Controlled release needle-suture combinations of the prior art have generally been characterized by a needle pulloff value within the range of 3 to 26 ounces. While this range is considered to be the preferred range for such needle-suture combinations, the U.S. Pharmacopeia has adopted a needle pulloff range of 0.028 to 1.59 kg (1 to 56 ounces) for sutures with "removable needles" and size 5-0 and larger as the standard for the suture industry.
It is accordingly an object of the present invention to provide a needle-suture combination having a removable needle within the specifications of the U.S. Pharmacopeia, i.e., with a needle pulloff value within the range of 1 to 56 ounces. It is a further object of the present invention to provide a needle-suture combination having a needle pulloff value within the preferred range of 3 to 26 ounces. It is a yet further object of the present invention to provide a controlled release needle-suture combination wherein the suture is secured within the axial opening of a surgical needle by means of a bonding composition which provides the needle with a pulloff value within the range of from about 1 to 56 ounces.
While adhesively bonded needle-suture combinations using drilled needles are known as described, for example, U.S. Pat. Nos. 2,928,395 and 3,394,704, conventional adhesives suggested in these references such as the polyepoxides, polyamides, polyesters, and urea resins do not reliably and consistently give needle pulloff values within the desired range for controlled release applications. These references are rather directed toward providing permanently attached needles having certain minimum, but no maximum, limits on needle attachment. The security of attachment of eyeless needles to absorbable surgical sutures or to nonabsorbable surgical sutures is prescribed in the U.S. Pharmacopeia, Vol. XVIII at page 944 (also see U.S. Pharmacopeia, Vol. XVII, p. 919). It has been the practice of suture manufacturers in the U.S. and abroad to securely attach the suture to the needle by swaging or with an adhesive so that the minimum pullout values recited in the U.S. Pharmacopeia are met or exceeded.